The furry, dark brown creatures hesitated at first and then shot out of their plywood cages and bounded into the forest near the hamlet of Stirling City.

It was the latest triumph in a remarkable campaign to bring back a long-lost predator known as the Pacific fisher to the northern Sierra Nevada.

The four stubby-legged mammals were released by California Department of Fish and Game biologists as part of an innovative effort to reintroduce the weasel family species to a region they were driven out of 100 years ago.

Three female fishers and one male were exposed to the dreaded sunshine - they're nocturnal - and gently prodded out of the open doors of their boxes onto Sierra Pacific Industries timberland in Butte County, bringing to 39 the total number of fishers moved into the area over the past three years. That's one less than the 40 fishers the reintroduction plan calls for.

"This is a milestone for us," said Richard Callas, a senior environmental scientist for the Department of Fish and Game, which is working with the U.S. Fish and Wildlife Service and North Carolina State University researchers. "We will continue to monitor them for the next three or four years. We want to see how they are using the land, what habitats are important, how they are faring and how they migrate to other areas."

Unusual partnership

The fisher program is the result of a highly unusual partnership with Sierra Pacific, one of the country's largest timber companies and the state's largest private landowner.

The idea was first broached in 2004, when Sierra Pacific offered Fish and Game officials five large tracts of land where fishers historically occurred but no longer existed. The department evaluated each plot and determined that a 168,000-acre tract of timberland near Stirling City, near Paradise Ridge, was the most suitable place to reintroduce the species.

Pacific fishers are cantankerous animals with lush fur, long slender bodies and short legs. They are related to martens, wolverines and weasels. The females are half the size of the males, which weigh about 10 pounds. They mate in the spring, but otherwise have little to do with one another.

Porcupine dinner

Fishers prefer dense old-growth forests where they can hunt in the trees and den in hollowed-out areas up high. They hunt squirrels, chipmunks and mice, and often scavenge carcasses and also eat roots and plant material. They are one of the few animals that kill and eat porcupines, going for the throat and then turning the spiny beasts over to feed on the stomach.

Curiously, though, fishers don't eat fish. It is believed they were named by early settlers who thought they looked like European polecats, also known in French as fiche or fitchet. The Dutch equivalent, visse, means "nasty."

The small, feisty mammals once ranged throughout the Sierra, Klamath, Cascade and Coastal ranges, but hunting, logging, development and habitat loss drastically reduced their numbers. In the early 20th century, fisher pelts, called North American sable, fetched hundreds of dollars.

Trapping banned

By 1946, when fur trapping of fishers was banned in California, the population had been reduced and was living in an area that was less than half of its former range. Fishers, for the most part, were wiped out in Oregon and Washington. Only two populations now exist in the state; on the border between the Klamath and coastal mountain ranges and the other in the southern Sierra, near Yosemite. Nobody knows exactly how many are left - they are notoriously difficult research subjects because they have wide ranges, leave few signs and assiduously avoid human contact - but recent estimates had them down to 850.

Fishers have been named as candidates for the endangered species list, but they have not been awarded the federal protection despite repeated warnings that they are perilously close to extinction. Fishers have been relocated to the Crater Lake area of Oregon and in Olympic National Park, in Washington, but this is the first time it has ever been done in California, Callas said.

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Sierra Pacific has agreed to manage its property over the next 20 years in a way that would benefit fisher mating, denning and habitat. In exchange, the company can expect regulatory leniency, including an incidental take permit, if the animals are ever listed under the Endangered Species Act. An incidental take permit is required when habitat modifications could injure or harm a listed animal.

Partnerships needed

Callas said partnerships with private landowners are the only way long-term, wide-ranging wildlife conservation recovery programs like this one can be accomplished.

"It is important because these animals have been absent from a substantial portion of their historic range," he said. "It puts more eggs in the conservation basket if landowners are willing to restore habitat and commit to protecting a species in an area where they have been missing for most of a century."

The animals that were relocated were trapped in a variety of different places at times of year when no mating was going on and the females were not raising young. Fifteen fishers were released at the site during the winter of 2009 and 2010, 13 animals were released last year, and 11 more have been released this year. Callas said he expects to capture and release one more male fisher this winter.

Tracking devices on the relocated animals show that most have remained in the area where they were released, but a few of the males have wandered as far as 60 miles.

"We had an animal that left Stirling and moved all the way to the Central Valley," he said. "We believe it crossed Highway 99 to the Sacramento River and then turned around and went back on a parallel course almost to the place where he was released. It was amazing."

Wildlife biologists and a team of researchers from North Carolina State will continue tracking and studying the fishers in the hope that they will learn more about the elusive animal's habits and one day help them repopulate their entire range.

Pacific fisher facts

-- About the size of a large house cat.

-- Member of the weasel family, which also includes minks, martens, otters and wolverines.

-- Lives up to 10 years.

-- Feeds on birds, rodents, reptiles, insects and vegetation. One of the few known predators of porcupines.

-- Range reduced dramatically in the 1800s and early 1900s through trapping, predator and pest control, logging, urbanization and farming.